Waterproofing and water elimination in basements is a subject of much attention because of the dismay caused by occasional water presence on basement floors. The present invention is the result of diligent and successful work in eliminating periods of water in the basement. In past years there would be surprise and alarm when finding water over the basement floor. Frantic effort would be required to undo the damage.
Conventionally a pump is placed in a well, pit or cavity ("sump") cut into the floor in or below the gravel, rock or mud bed which is found under basement floors. Channel drains on the floor, drainpipes under the floor, or gutters around the base of the basement walls direct water to the sump. The sump pump, usually controlled by a float, pumps the water in the sump out of the basement through an outflow piped away from the house when the water exceeds a predetermined depth.
Sumps take away floor space--a common sump will measure several square feet--and are troublesome to install in existing basements. The conventional float control is prone to problems due to mechanical interference with the float mechanism, thus requiring clear space around the float, especially for a hinged float, which in turn increases the required sump size. Hoses or debris in the water can hold the float under water, preventing it from turning on the pump, or such objects can slip under the float, causing the pump motor to run continuously. Corrosion on the float hinge or slip rod can cause the float to hang up. In addition, the water level is not well controlled by float switches, and the process of floatation requires a certain amount of water to physically support the float sufficiently to activate a switch. In short, float switches are subject to jamming, require much space, and need wide water height variations.
If the basement floor is built on a mud, clay or compressed soil base, the under-floor drainage could be poor enough that even when the water level in the sump is kept low by the sump pump, water will still seep into the basement at other points. If possible, this water may need to be drained into the sump across the floor or through the channels or gutters. In some cases, the water will collect in low spots on the concrete floor during wet periods and cannot be removed at all except by evaporation and a dehumidifier.
Thus, in a conventional sump system, some quantity of water is nearly always present in the basement, either as unpumped water in the sump, or flowing down channels or gutters to the sump, or even as standing surface water in low spots. This increases the humidity in the basement and potentially damages any floor covering which might be present. The sump, gutters and/or collection drains are unsightly, as well.